Nonstick roll contact for contact relays, circuit breakers, thermostats, and the like



Oct. 18, 1949.v c.-w. JOHNSON NONSTIGK ROLL-CONTACT FOR CONTACT RELAY S CIiRCUIT 1 BREAKERS, THERMOSTATS, AND THE LIKE Filed Oct. 1, 1948 v I I 121/17627/1172'. A 67166362" W JOE/n50 n,

'- flaw-7M Patented Oct. 18, 1949 NONSTICK RoLL CONTACT FOR CoNTACT RELAYS, CIRCUIT BREAKERS, THERMO- sTATs, AND THE LIKE Chester W. Johnson, Bridgewater, Mass, assignor of one-half to Larry M. Hess, Taunton, Mass, and one-fourth t Everett D. Copeland, South Hanson, Mass.

Application October 1, 1948, Serial No. 52,364

I 2 Claims. 1 This invention relates to non-stick roll-contacts for contact relays, circuit breakers, thermostats and the like.

In order that the principle of the invention may be readily understood, I have disclosed a single embodiment thereof in :the accompanying drawing, wherein- Fig. 1 is a side elevation of a roll-contact relay with the roll-contacts in open or separated condition;

Fig. 2 is a side elevation of the same construction showing the roll contacts in closed position in contact with each other;

Fig. 3 is an end view of the construction shown in Fig. 1, the roll-contacts being in open position;

Fig. 4 a plan View of the construction shown in Fig. 1; and

Fig. 5 is a side view of a thermostat having my invention applied thereto.

The purpose of my invention is to providea contact-roll type of contact in a relay, circuit breaker, thermostat and the like, that will give a positive make-and-break for practically an unnumbered amount of cycles. For this purpose both of the contacts are formed as rolls freely mounted upon their pivots or axles or in the supports for the axles, and preferably so related to each other that as roll-contacts separate upon interruption of the current, and when they are again brought into contact upon renewal of the current, one or both of said contact-rolls is or are turned slightly upon or with the pivot or pivots thereof, so as to present .a different area of contact from the last preceding contact. This result I preferablyaccomplish by so mounting the said contact-rolls upon their supports that when they are in peripheral Contact with each other, the pivot or axis of one of said contact-rolls is slightly lower than the pivot or axis of the other contact-roll, for the purpose of causing a slight turning movement of one and preferably both contact-rolls as they separate upon interruption of the current and as they again contact upon renewal of the current, that is, upon reenergization of the relay, circuit breaker, thermostat or the like. Because of this construction and result, any welding or building up action that takes place or :tends to take place in an ordinar relay or like contact is eliminated, and by reason of the fact that the contact-rolls are of relatively large diameter they present large cooling areas.

Referring more particularly to the drawing, and first to Figs. 1 :to 4 thereof, I have therein represented a relay, but it is to be understood that my invention is in no wise limited to a relay, whether of a single, double or triple type, but is equally well adapted to circuit breakers, thermostats and the like.

In said Figs. 1 to 4, the base of an ordinary relay is represented at I. It may be of any suitable material, as, for example, Bakelite, and thereon is supported in any suitable manner a Core 2 which at its upper end maybe provided with a Bakelite member or portion 3. Suitably supported at one side of the core 2 upon the base I is a bracket-like member 4, to which in any suitable manner, near the upper end thereof, as at 5, there is suitably pivoted or similarly mounted a so-called clapper 6, which, as shown in said figures, extends inwardly from its pivot over the core 2, so that when the latter is energized the clapper 6 is moved downwardly against the tension of a coiled spring 1, the lower end of which is connected at 8 to a lateral extension of the bracket 4 and the upper end of which is connected to a threaded part 9 received in and extending through an opening in the outer end of the clapper 6 and having desirably a nut I0 so that the part 9 can be adjusted up and down to vary the tension of the spring 1, the upper end of which extends through an eye or hook portion at the lower end of the part 9. I

At or near the inner end of the clapper 6 there is preferably provided an insulating strip ll of Bakelite or other suitable material, and mounted upon said Bakelite strip there is a bracket l2 supporting one or desirably a pair of parallel contact-roll supporting members l3 having near their outer ends openings to receive the pivot M of a contact-roll A. While the roll A may be of any suitable material, I preferably form it of bronze, and provide it with a suitable contact surface which desirably is silver, as being less expensive than platinum, which, however, may be employed, as may any other suitable material. Desirably the roll A is about five times larger than the ordinary relay contact, but, of course, this may be varied substantially Within the scope Of my, invention. My experimentation and tests indicate thus far that when employing a current of about volts, 14 amperes, a contact-roll that is about one-quarter inch wide and about a half inch in diameter gives excellent results, but the scope of the invention is in no wise to be limited by these figures. With a greater amperage the contact-rolls should be greater in diameter and Width.

The silver or other suitable surface of the roll A is indicated at A, and for the best results,

so far as my tests have determined, the thickness of the silver wall should be about one-sixteenth of an inch. In order to provide such silver surface, I desirably provide a silver tube, the wall whereof is of substantially one-sixteenth of an inch in thickness, and the internal diameter of which tube very slightly exceeds the diameter of the bronze or like roll A, so that by cutting from an end of the silver tube a small portion of the width of the roll A, it can be forced thereonto in any suitable manner, so that the roll A and its silver or other surface A rotate as a unit.

In order to provide the second roll-contact, which is indicated at B, I preferably secure to the Bakelite base I the lower end of a relatively thin and relatively narrow plate-spring l5, so that the same extends upward in parallelism with the axis of the core 2, and at a slight distance from said core. Upon the upper end of said plate-spring l5 there is secured a small bracket it from which upwardly extends one and preferably two supporting members l1, each having an opening near its upper end to receive the pivot or axle of the roll-contact B, which is formed in the same manner as the roll-contact A, being desirably of the same size. Desirably also the peripheral surfaces of the roll-contacts A and B (namely, the silver surface A of the roll A and the silver surface B of the roll B) are smooth, as I have obtained the best results by so constructing them.

Referring to Fig. 2, wherein the two roll-contacts A, B, are in contact with each other, it will be observed that, the core 2 having been energized, the clapper 6 has been drawn down by the magnetic pull of the core 2 and that the silver surface of the roll-contact A has been brought into contact with the like surface of the rollcontact B, and in so doing the plate spring l5 has been slightly flexed outwardly. The pivot or axle of the roll-contact B is slightly lower than the pivot or axle of the roll-contact A even when the two rolls A and B are in-contact. The result is that when the roll-contact A is brought into contact with the roll-contact B by the magnetic pull of the core 2, both of the roll-contacts A and B are very slightly turned upon or with their pivots or axles so that both of them, or at least one of them, present a different circumferential area of contact than when the said roll-contacts were last previously brought into contact by the last preceding energization of the core 2 of the relay.

When the core is deenergized the coil spring 1 at once lifts the roll-contact A from contact with the roll-contact B, and the plate spring i5 which supports the roll B instantly moves the said roll B inward, and as the pivot of the rollcontact B is slightly lower than the pivot of the roll-contact A, the result is that both of said rollcontacts are given a slight rotation upon or withtheir respective axes as they separate. Thus when the said roll-contacts A and B are then brought into contact by the energization of the core 2, the said roll-contacts, either or both, present a different contact area because of the said turning movement of one or both of said rollcontacts A and B.

It is unnecessary to refer in detail to the wiring extending to the relay and to the roll-contacts A and B, since it may be the same as is usually provided. However, in Fig. 4, there is most clearly shown the lead wires that are provided for the purpose. These lead wires may be of the usual construction and arrangement used in relays, circuit breakers, thermostats and the like.

Referring therefore more particularly to Fig. 4, the following construction is there shown.

Referring not only to Fig. but to Figs. 1, 2 and 3, there are shown four binding posts l8, i9, 20, 2! mounted in the Bakelite base I. Extending from the binding post 2| is a lead 22 which is held in position by locking screw 23, thus connecting said lead 22 to the upright plate spring I5. Extending from the binding post I9 is a lead 24 which extends up to and is connected to the clapper 5. Extending from the binding posts l8 and 20 are two leads 25 and 2B which extend into the coil 2.

It is noted that the contact-rolls A and B are held in position upon their pivots by cotter pins 21, 28 at one end of their pivots. This permits the rolls A and B to be readily renewed if and when they become worn. This is preferably done by making the contact rolls loose upon their pivots which are held supported, as described, in the supporting members l3 and H. In order to renew the rolls A and B, or either of them, the pivot or axle for each of the rolls is removed from its support l3 or I! by first removing the cotter pins and then sliding the contact rolls A and B off their pivots or axles.

If desired, the pivots or axles for the contactrolls A, B may be formed as rods threaded at one end and having a head at the other end. In such case the headed end engages one of the supports E3 or H and the threaded end is threaded into the other support 83 or I I, and then a cotter pin is passed through a suitable hole in the threaded projecting end of the pin, so that the pivot or axle is held without turning in the supports l3 or I.

I have stated that in operation both the contact-rolls A and B turn. My tests show that the upper roll A turns to a greater extent than the lower roll B at a ratio of approximately two to one. In any event both rolls turn sufiiciently to present a new surface when they next contact with each other.

In Fig. 5, I have represented in side elevation a thermostat consisting of a rigid metal strip 29 and a bi-metal strip 30 connected together by a Bakelite or other insulation 3|. Extending from the rigid metal strip 29 is a lead 32, and extending from the bi-m'etal strip 30 is a lead 33. These extend to any points desired, in accordance with usual practice, for opening and closing a thermostatic circuit.

Upon the outer or left-hand end, viewing Fig. 5, of the strips 28 and 3!] are mounted, in a manner preferably entirely similar to that shown in Figs. 1, 2 and two contact-rolls 34 and 35, the action of which is the same as that of the contact-rolls A and B already described. Between the strips 29 and 30 I provide a non-conducting stop 35.

It will be understood that when the clapper B is drawn downwardly by the magnetic pull of the core 2 and the roll A contacts with the roll B, the plate spring or like support [5 for the roll-contact B is flexed slightly outward into the position shown in Fig. 2.

Having thus described one illustrative embodiment of the invention, it is to be understood that although specific terms are employed, they are used in a generic and descriptive sense and not for purposes of limitation, the scope of the invention, being set forth in the following claims.

I claim:

1. In a relay, circuit breaker, thermostat and the like, two smooth surfaced contact rolls having suitable wiring connections to a source of current,

I: I.) said two contact rolls being of substantially equal diameter and mounted upon their axes in parallelism for absolutely free rotation thereon, the said rolls being, therefore, both free of restraint against rotation upon their axes in either direction at all times, one of said rolls being mounted upon its axis only slightly higher than the axis of the other roll and slightly to one side thereof when said rolls are out of contact, with the upper roll at the limit of its non-contacting movement, so that when the higher of said rolls is moved down into contact with the lower roll in an arc in the normal operation of said relay or the like, it strikes the lower roll at one side thereof but above the axis thereof, and its imparts, as the result of each contact, a slight turning movement to said lower roll and itself receives a slight turning movement in the opposite direction, spring means acting upon the interruption of current to move the said upper roll in a non-contacting movement up and away from the said lower contact roll, and a spring support for the lower contact roll tending to move it in an arc toward the lower part of said upper contact roll, the said turning movement of both of said rolls also occurring in the act of separation of the said two contact rolls, whereby, when said contact rolls next contact, a circumferentially, slightly different, contact area is presented by both of said rolls, and whereby such presentation of different contact areas occurs upon all successive contacts in the normal operation of said relay or the like.

2. A relay, circuit breaker, thermostat and the like in accordance with claim 1, wherein each of said contact rolls has a silver circumferential surface.

CHESTER W. JOHNSON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,023,102 Badeau Apr. 9, 1912 20 1,357,942 Ballman Nov. 9, 1920 1,690,538 House Nov. 6, 1928 FOREIGN PATENTS Number Country Date 127,445 Germany Jan. 21, 1902 

